The reports of the IPCC and the scientific consensus they reflect have provided one of the most prominent bases for the formulation of climate-change policy. On a global scale, climate-change policy is guided by two major treaties: the United Nations Framework Convention on Climate Change (UNFCCC) of 1992 and the associated 1997 Kyoto Protocol to the UNFCCC (named after the city in Japan where it was concluded).

The UNFCCC was negotiated between 1991 and 1992. It was adopted at the United Nations Conference on Environment and Development in Rio de Janeiro in June 1992 and became legally binding in March 1994. In Article 2 the UNFCCC sets the long-term objective of “stabilization of greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system.” Article 3 establishes that the world’s countries have “common but differentiated responsibilities,” meaning that all countries share an obligation to act—though industrialized countries have a particular responsibility to take the lead in reducing emissions because of their relative contribution to the problem in the past. To this end, the UNFCCC Annex I lists 41 specific industrialized countries and countries with economies in transition plus the European Community (EC; formally succeeded by the EU in 2009), and Article 4 states that these countries should work to reduce their anthropogenic emissions to 1990 levels. However, no deadline is set for this target. Moreover, the UNFCCC does not assign any specific reduction commitments to non-Annex I countries (that is, developing countries).

The follow-up agreement to the UNFCCC, the Kyoto Protocol, was negotiated between 1995 and 1997 and was adopted in December 1997. The Kyoto Protocol regulates six greenhouse gases released through human activities: carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), perfluorocarbons (PFCs), hydrofluorocarbons (HFCs), and sulfur hexafluoride (SF6). Under the Kyoto Protocol, Annex I countries are required to reduce their aggregate emissions of greenhouse gases to 5.2 percent below their 1990 levels by no later than 2012. Toward this goal, the protocol sets individual reduction targets for each Annex I country. These targets require the reduction of greenhouse gases in most countries, but they also allow increased emissions from others. For example, the protocol requires the then 15 member states of the EU and 11 other European countries to reduce their emissions to 8 percent below their 1990 emission levels, whereas Iceland, a country that produces relatively small amounts of greenhouse gases, may increase its emissions as much as 10 percent above its 1990 level. In addition, the Kyoto Protocol requires three countries—New Zealand, Ukraine, and Russia—to freeze their emissions at 1990 levels.

The Kyoto Protocol outlines five requisites by which Annex I parties can choose to meet their 2012 emission targets. First, it requires the development of national policies and measures that lower domestic greenhouse gas emissions. Second, countries may calculate the benefits from domestic carbon sinks that soak up more carbon than they emit (seeCarbon cycle feedbacks). Third, countries can participate in schemes that trade emissions with other Annex I countries. Fourth, signatory countries may create joint implementation programs with other Annex I parties and receive credit for such projects that lower emissions. Fifth, countries may receive credit for lowering the emissions in non-Annex I countries through a “clean development” mechanism, such as investing in the building of a new wind power project.

In order to go into effect, the Kyoto Protocol had to be ratified by at least 55 countries, including enough Annex I countries to account for at least 55 percent of that group’s total greenhouse gas emissions. More than 55 countries quickly ratified the protocol, including all the Annex I countries except for Russia, the United States, and Australia. (Russia and Australia ratified the protocol in 2005 and 2007, respectively.) It was not until Russia, under heavy pressure from the EU, ratified the protocol that it became legally binding in February 2005.

The most-developed regional climate-change policy to date has been formulated by the EU in part to meet its commitments under the Kyoto Protocol. By 2005 the 15 EU countries that have a collective commitment under the protocol reduced their greenhouse gas emissions to 2 percent below their 1990 levels, though it is not certain that they will meet their 8 percent reduction target by 2012. In 2007 the EU set a collective goal for all 27 member states to reduce their greenhouse gas emissions by 20 percent below 1990 levels by the year 2020. As part of its effort to achieve this goal, the EU in 2005 established the world’s first multilateral trading scheme for carbon dioxide emissions, covering more than 11,500 large installations across its member states.

In the United States, by contrast, Pres. George W. Bush and a majority of senators rejected the Kyoto Protocol, citing the lack of compulsory emission reductions for developing countries as a particular grievance. At the same time, U.S. federal policy does not set any mandatory restrictions on greenhouse gas emissions, and U.S. emissions increased over 16 percent between 1990 and 2005. Partly to make up for a lack of direction at the federal level, many individual U.S. states have formulated their own action plans to address global warming and climate change and have taken a host of legal and political initiatives to curb emissions. These initiatives include: capping emissions from power plants, establishing renewable portfolio standards requiring electricity providers to obtain a minimum percentage of their power from renewable sources, developing vehicle emissions and fuel standards, and adopting “green building” standards.

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